The present invention relates generally to sockets for tooling, e.g., socket wrenches, torque wrenches or air wrenches, used to apply torque to hardware, e.g., nuts or bolts, in an assembly process. More specifically, the present invention relates to a protective socket which prevents marring and/or damaging hardware or components being assembled when torque is applied.
Sockets and their associated tooling are used in a wide variety of applications throughout many different industries to assemble and attach various components by applying torque to hardware to hold the components together. The sockets themselves are generally constructed of a metal, such as steel, capable of applying the proper torque to the hardware without deformation. However, when torque is applied, the socket can damage or mar the hardware or the components being assembled. That is, the corners on the head of a nut or bolt can be rounded off, the paint or coating can be damaged or scraped off the hardware, or the component itself can be scraped or scratched as the socket twists against its surface.
In many industries, e.g., aircraft, automotive, ship building, medical equipment and nuclear, the damage and marring caused by torquing, i.e., tightening or loosening, the sockets requires corrective action. By way of example, in the aircraft industry, damage caused by torquing prior art sockets to the required load may result in the following problems: (1) damaged hardware or components are considered a safety hazard and must be replaced; (2) chipped or damaged protective finishes on various hardware or components are considered contamination in aircraft critical areas or a safety hazard; (3) aircraft quality control standards require aircraft manufacturers to initiate costly and time consuming material review procedures to identify damaged components or hardware bolts and determine proper corrective action; and (4) corrective action procedures often require aircraft manufacturers to disassemble and strip the protective coating from damaged components or hardware, then recoat and reassemble. It is very common for these corrective action procedures to be repeated numerous times during the assembly process.
Various non-metallic sockets, e.g., nylon, Teflon(copyright), or other polymeric materials, have been utilized in an attempt to prevent the marring and damaging caused by metallic sockets. However, these non-metallic sockets require a larger outside diameter than the metallic sockets in order to obtain the strength necessary to apply the proper torque to the hardware during an assembly process. These larger outside diameters prevent the non-metallic sockets from fitting inside standard counter bores associated with the hardware, e.g. a xe2x85x9c inch bolt requires 0.620 inch diameter counter bore and xc2xe inch bolt requires a 1.120 inch diameter counter bore. On the other hand, if the non-metallic sockets outside diameter were made small enough to fit into the counter bores they would lack the strength of the metallic sockets and deform or slip when applying torque to the hardware.
The accepted US standard for counter bore diameters for conventional socket wrenches, e.g. detachable socket wrenches with xc2xc inch and xe2x85x9c inch square drives for hand use (manufactured to standard ASME B107.1-1993), is cited as follows: xe2x80x9cWrench Clearance, Table 3, SAE Aeronautical Drafting Manual, 1954 edition, page Y4.04xe2x80x9d (hereinafter the xe2x80x9cSAE Standardxe2x80x9d). The standard is published by the SAE INTERNATIONAL, 400 Commonwealth Drive, Warrendale, Pa. 15096-0001. Column xe2x80x9cAxe2x80x9d of the SAE Standard gives the associated minimum counter bore diameters required to receive the nut drive end of the above referenced socket wrenches. The SAE Standard has been adopted and used by the machinery industry for many years and is printed in the 25th Edition of the xe2x80x9cMachinery Handbookxe2x80x9d, published by Industrial Press, Inc., New York, N.Y. (hereinafter the xe2x80x9cMachinery Handbookxe2x80x9d). Column xe2x80x9cAxe2x80x9d of the SAE Standard is printed as column xe2x80x9cKxe2x80x9d on page 1436 of the Machinery Handbook in Table 2, titled xe2x80x9cWrench Clearances for Open End Wrench 15 degrees and Socket Wrench (Regular Length)xe2x80x9d. The socket wrench hardware sizes and associated minimum counter bore diameters of Column xe2x80x9cAxe2x80x9d of the SAE Standard are reprinted in the following table:
One such prior art socket wrench having a non-marring insert is described in U.S. Pat. No. 3,433,108 to E. J. Ondeck (hereinafter the xe2x80x9cOndeck patentxe2x80x9d). The Ondeck patent is directed to a socket wrench having a non-mar plastic insert having longitudinal side-walls adapted to fully engage a like number of side-walls in a wrench socket in sliding fit relationship and an inner cross-section having longitudinal side-walls. The insert has the same number of outer side-walls as the socket and the same number of inside walls as the nut with which it is used. The insert has 24 outside walls (or 12 corners mating with a conventional socket wrench) and provides in combination therewith six inside walls (or 6 points) for use with hexagonally headed nuts.
However, the problem of having a socket wrench with both a non-mar inner lining and an outside diameter which meets the SAE Standard is not solved by Ondeck. It is specifically stated in Ondeck that, once the insert is fit into a conventional socket wrench, e.g., one manufactured to standard ASME B107.1-1993 (inch series) or ASME B107.5M-1994 (metric series), than xe2x80x9cthe plastic liner or adaptor is constructed to cooperate with a nut slightly smaller in dimension than a nut properly fitting in the socket without the linerxe2x80x9d (see Ondeck, column 3, lines 41-43). This is because the plastic non-mar liner of Ondeck would xe2x80x9cflowxe2x80x9d or deform if the soft plastic insert were to be made any thinner. Even with the combination of the conventional wall thickness of a standard socket wrench for added support, the soft plastic insert of Ondeck must have a geometric shape in which no voids exist between the inserts hexagonal inner surface and the nut to be engaged or plastic flow will occur and the insert will be damaged (see Ondeck, column 3, lines 24-28).
The problem in Ondeck, as in other non-mar prior art sockets, is that a non-marring inner lining must be inherently softer that the nut it is designed to engage in order to prevent marring. Therefore, the inner lining must rely on its outer sleeve for added support or the nut will damage the inner lining. A delicate balance must be struck between the hardness of the nuts to be engaged, the hardness and geometry of the non-mar inner lining, and the hardness and geometry of a socket""s outer sleeve. This balance becomes all the more difficult and complex when the outside diameter of the socket wrench must also be limited to the SAE Standard for minimum counter bore diameters. It is also this balance which forces the dimensions of prior art sockets away from conventional socket wrench standards, such as ASME B107.1-1993 and ASME B107.5M-1994.
There is a need, therefore, for an improved non-mar socket wrench, which can also fit within the dimensional parameters of conventional socket wrench standards, such as the SAE Standard, ASME B107.1-1993 or ASME B107.5M-1994.
This invention offers advantages and alternatives over the prior art by providing a protective socket having an outer sleeve and an inner lining with dimensions which substantially meet conventional socket wrench standards, such as the SAE Standard, ASME B107.1-1993 or ASME B107.5M-1994. Advantageously, the outer sleeve reinforces the inner lining to provide the strength required to torque hardware during most assembly processes. Also, the outer sleeve is preferably sized to fit into the SAE Standard counter bores of the associated hardware being torqued and the inner lining preferably extends outwardly from a distal end of the outer sleeve. Additionally, the inner lining is pliable enough to prevent damaging or marring of the hardware or components being assembled. This advantageously reduces the reassembly, corrective action and safety hazards associated with the damaged and marred components and hardware. This results in significant assembly cost savings in industries with critical quality control standards, such as the aircraft industry, automotive or nuclear industry.
These and other advantages are accomplished in a preferred form of the invention by providing a socket adapted to torque a head of a hardware fastener. The hardware having a predetermined size and an associated counter bore with a predetermined diameter per the SAE Standard cited as: xe2x80x9cWrench Clearance, Table 3, SAE Aeronautical Drafting Manual, 1954 edition, page Y4.04xe2x80x9d. The socket comprises a drive portion adopted to engage a socket drive tool, and a hardware portion attached to the drive portion. The hardware portion includes a metallic outer sleeve having an outside diameter which is sized to fit into the associated counter bore of the hardware, and a non-marring inner lining disposed within the outer sleeve. The inner lining includes a hardware torquing hole located at a distal end of the socket, and sized to fit over the head of the hardware to provide torquing to the hardware without marring the hardware. Preferably, the inner lining has an M scale hardness of substantially 115 or greater and is comprised of a composite material.
In an alternative embodiment the socket has dimensions which substantially meet standard ASME B107.1-1993 (inch series). In another alternative embodiment the socket has dimensions which substantially meet standard B107.5M (metric series).